The expressions for the sum to n terms of some arithmetic sequences are given below. Find the expression for the nth term of each:
2n2 + n
Sn = 2n2 + n
an + 1 = Sn + 1 - Sn
= {2(n + 1)2 + (n + 1)}- {2n2 + n}
= (2n2 + 4n + 4 + n + 1)-(2n2 + n)
= 4n + 5
= 4(n + 1) + 1
∴ an = 4n + 1
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